Does the ultraviolet light treatment for shoes really work in helping to prevent toenail fungus? Thank you.

I would say . It is an adjunct treatment. It is helpful of possibly preventing contamination. I am not sure i would recommend it as a preventative measure but more as a treatment in a case of recalcitrant fungus that doesn't go away.
Yes. But the way it works is to sterilize the shoe which cuts down the chance of fungus from within the shoe.